A thermal power plant is a power generation apparatus that generates power by driving a power generation apparatus using combustion heat taken out through combustion mainly of fossil fuel, and various types of power generation apparatuses are present depending on combinations of fuel and the power generation apparatus. Examples of such apparatuses include a steam turbine power generation apparatus that generates power by burning coal or heavy oil in a boiler and generating steam using combustion heat therefrom to drive a steam turbine, a gas turbine power generation apparatus that generates power by compressing atmospheric air with a compressor, mixing and burning the compressed air with fuel in a combustor, and driving a gas turbine using combustion air therefrom, or a combined cycle power generation apparatus that generates steam in an exhaust heat recovery boiler using an exhaust gas burned in a gas turbine and drives a steam turbine with the steam.
Meanwhile, power generation using renewable energy, such as natural energy, has been attracting attentions from a viewpoint of reducing carbon dioxide. In particular, power generation using wind power generation or solar power generation has been rapidly spreading. However, it is not possible to control natural conditions, and power generation output to be obtained is not constant but varies. If such a power supply is connected to a system, the system becomes unstable, and there is a risk that it is difficult to keep a constant frequency of the system. In addition, the steam power generation, such as the power generation using a gas turbine, is generally designed to reach the maximum efficiency at the time of application of a rated load, and thus, the efficiency decreases during an operation with a partial load.
PTL 1 discloses a control apparatus that issues a power generation instruction according to the system load and adjusts an exhaust heat recovery volume or a heat storage volume of a thermoelectric load in a power system in which a plurality of power supplies and thermoelectric loads having different volumes, such as a gas engine and a gas turbine power generator, are connected to correspond to unstable power supply of wind power generation or solar power generation.
PTL 2 discloses a combined plant that supplies surplus power obtained by wind power generation equipment and gas turbine equipment heavy oil reformation equipment.
PTL 3 discloses a system that realizes improvement in efficiency of a partial load by connecting an auxiliary power generator/motor to a multi-shaft gas turbine engine including a plurality of spools and injecting mechanical power into the spools or extracting the mechanical power from the spools.